U.S. patent application number 10/776611 was filed with the patent office on 2004-08-19 for voltage detecting apparatus applicable to a combination battery.
This patent application is currently assigned to DENSO CORPOATION. Invention is credited to Fujita, Hiroshi, Kito, Yuji.
Application Number | 20040160229 10/776611 |
Document ID | / |
Family ID | 32844522 |
Filed Date | 2004-08-19 |
United States Patent
Application |
20040160229 |
Kind Code |
A1 |
Fujita, Hiroshi ; et
al. |
August 19, 2004 |
Voltage detecting apparatus applicable to a combination battery
Abstract
A voltage detecting apparatus for a combination battery includes
a multiplexer type flying capacitor voltage detecting circuit, a
synchronous control type A/D converter, and a battery controller.
The battery controller has a timing table to regulate generation
timings of a switching control signal, an activation signal, and a
transfer command signal on a common time axis. The timing control
is carried out by outputting the switching control signal, the
activation signal, and the transfer command signal to the flying
capacitor voltage detecting circuit, the A/D converter, and the
battery controller at the timing regulated in the timing table and
according to an order memorized in the timing table.
Inventors: |
Fujita, Hiroshi;
(Kuwana-shi, JP) ; Kito, Yuji; (Nagoya,
JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
DENSO CORPOATION
Kariya-city
JP
|
Family ID: |
32844522 |
Appl. No.: |
10/776611 |
Filed: |
February 12, 2004 |
Current U.S.
Class: |
324/607 |
Current CPC
Class: |
Y02T 10/70 20130101;
B60L 50/72 20190201; B60L 58/21 20190201; B60L 3/12 20130101; G01R
31/3835 20190101; Y02T 90/34 20130101; Y02T 90/40 20130101; B60L
2270/147 20130101; Y02T 10/7061 20130101; B60L 3/0038 20130101;
G01R 31/396 20190101; B60L 2240/547 20130101 |
Class at
Publication: |
324/607 |
International
Class: |
H01F 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 2003 |
JP |
2003-041354 |
Claims
What is claimed is:
1. A voltage detecting apparatus for a combination battery
comprising: a multiplexer type flying capacitor voltage detecting
circuit having an input multiplexer and an output side sampling
switch, whose operation timing is controlled in response to an
entered switching control signal for time sequentially executing
voltage read-in processing and voltage read-out processing to
detect the voltage of a plurality of battery modules of a
combination battery in a time sequential fashion; a synchronous
control type A/D converter whose operation timing is controlled in
response to an entered activation signal for sample holding and A/D
converting an analog output voltage of said flying capacitor
voltage detecting circuit, and holding a digital voltage signal as
a resulting output until a succeeding digital voltage signal is
obtained; and a battery controller whose operation timing is
controlled in response to an entered transfer command signal for
reading said digital voltage signal produced from said A/D
converter and storing the readout digital voltage signal into a
data storage area assigned to each of said battery modules, wherein
said battery controller comprises a timing table on which
generation timings of said switching control signal, said
activation signal, and said transfer command signal are all
determined on a common time axis, and timing control for said
flying capacitor voltage detecting circuit, said A/D converter, and
said battery controller is carried out by outputting said switching
control signal, said activation signal, and said transfer command
signal to said flying capacitor voltage detecting circuit, said A/D
converter, and said battery controller at the timing regulated in
said timing table and according to an order memorized in said
timing table.
2. The voltage detecting apparatus for a combination battery in
accordance with claim 1, wherein said battery controller gives
first priority to the output of said switching control signal
supplied to said flying capacitor voltage detecting circuit in a
case that said timing table regulates signal generation timings in
such a manner that the generation timing of said switching control
signal equals to or overlaps with the generation timing of said
activation signal or said transfer command signal.
3. The voltage detecting apparatus for a combination battery in
accordance with claim 1, wherein said timing table sets the timing
of said activation signal in such a manner that a voltage read-in
timing of said A/D converter does not involve a switching timing of
said flying capacitor voltage detecting circuit and a switching
timing for data storage of said battery controller.
4. The voltage detecting apparatus for a combination battery in
accordance with claim 1, wherein said timing table includes a first
small table for designating the timing of said switching control
signal and a second small table for designating the timing of said
activation signal and said transfer command signal, being
respectively regulated on the common time axis, and said battery
controller refers to said first small table at time intervals
shorter than those of said second small table.
5. A voltage detecting apparatus for a combination battery,
comprising a flying capacitor voltage detecting circuit having an
input multiplexer and an output side sampling switch and executing
voltage read-in processing and voltage read-out processing in a
time sequential fashion to detect the voltage of a plurality of
battery modules of a combination battery; an A/D converter for A/D
converting an analog output voltage of said flying capacitor
voltage detecting circuit into a digital voltage signal; and a
battery controller for reading said digital voltage signal produced
from said A/D converter and storing the readout digital voltage
signal into a data storage area assigned to each of said battery
modules, wherein said battery controller comprises a read-out order
memory table for regulating voltage detection order of respective
battery modules, said battery controller writes identification
numbers of battery modules into said read-out order memory table in
order of voltage largeness of respective modules detected
previously, and said battery controller controls said input
multiplexer of said flying capacitor voltage detecting circuit in
such a manner that, in the next voltage read-out processing of
respective modules, the module voltages are successively read out
in accordance with the order memorized in said read-out order
memory table.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a flying capacitor battery
voltage detecting apparatus.
[0002] A flying capacitor voltage detecting circuit is known as a
voltage detecting apparatus preferably applicable to a combination
battery which includes a plurality of battery modules, each
including a single or a plurality of serially connected cells,
which are arranged in series. This flying capacitor voltage
detecting circuit performs the voltage read-in processing for
sample holding the voltage of a voltage source in a flying
capacitor in response to turning-on of an input side sampling
switch and the voltage read-out processing for applying a charged
voltage of the flying capacitor between a pair of input terminals
of a differential amplification circuit by turning on an output
side sampling switch after the input side sampling switch is turned
off.
[0003] Nowadays, a digital signal processing based on a
microcomputer or a comparable processor is generally used in the
computation processing for a detected module voltage of the
combination battery. And, it is necessary to cause an A/D converter
to execute the A/D conversion applied to the analog output voltage
produced from the differential amplification circuit and also cause
a microcomputer-based battery controller to read the A/D converted
data in a time sequential fashion.
[0004] Namely, the module voltage detection using a flying
capacitor voltage detecting circuit necessarily requires the
voltage read-in processing, the voltage read-out processing, the
A/D conversion processing, and the data transfer processing for
transferring the digital voltage signal to a data memory of the
microcomputer, as described above, for each of the battery
modules.
[0005] In this case, the A/D conversion processing is an operation
for sample holding the analog output voltage of the differential
amplification circuit at the designated sample hold timing and
executing the A/D conversion of the sampled voltage, and then
holding a produced digital voltage signal until a succeeding
digital voltage signal is produced. The data transfer processing is
an operation for supplying the digital voltage signal being held at
an output section of the A/D converter into an input port of the
microcomputer and for storing the readout voltage data in a
predetermined memory area of the microcomputer. The A/D converter
needs to successively execute the A/D conversion applied to the
module voltage produced from the differential amplification
circuit. The microcomputer needs to successively write the digital
voltage signal appearing at the output section of the A/D converter
into its memory area.
[0006] However, hybrid vehicles, motor-driven vehicles, fuel-cell
vehicles are equipped with a combination battery generally
consisting of several hundreds of cells being connected in series.
The combination battery is generally divided into several tens or
several hundreds of battery modules. As a result, to accomplish the
voltage detection of the combination battery entirely, each battery
module needs to execute the above-described voltage read-in
processing, the voltage read-out processing, the A/D conversion
processing, and the data transfer processing to the data memory of
the microcomputer at appropriate timings.
[0007] If the module voltage detecting operations of respective
battery modules are executed in parallel with each other, the
processing time will be substantially extendable. However, the
scale for such a circuit will become too big to realize.
Accordingly, it is usual that the input side sampling switch of a
flying capacitor voltage detecting circuit is constituted by a
multiplexer so that several tens or several hundreds of module
voltages can be read into a single or a plurality of flying
capacitors in a time sequential manner.
[0008] However, using the multiplexer serving as an input side
sampling switch will complicate the above-described voltage read-in
processing due to necessary switching control for the multiplexer.
The time sequential control of various portions of the voltage
detecting apparatus of a combination battery will become further
complicated. The processing time available for each module voltage
will be greatly reduced. As a result, the allocated time for the
voltage read-in processing (i.e., the essential CR charging
operation) becomes short. In other words, the flying capacitor will
not be saturated with charging. It becomes difficult to accurately
execute the voltage read-in processing. Furthermore, the
computation load of the microcomputer will become large. The
microcomputer will be subjected to the incoming noises accompanying
the complicated and speedy switching controls of various portions.
Due to adverse influence of the noises, the control timings will be
so asynchronous to result in erroneous detection.
[0009] To solve this problem, the Japanese Patent Application
Laid-open No. 2002-156392 proposes a parallel read-in system
including a plurality of flying capacitors arranged in parallel to
each other to read module voltages through a multiplexer. However,
if the number of flying capacitors and the A/D converters is not
increased, a multiplexer serving as an output side sampling switch
will be necessary for the voltage read-out processing. The
switching control, i.e., timing control, of a circuit system is not
simple. The microcomputer will be still bothered with a large
processing or computation burden for the A/D conversion processing
and the storage processing. In this manner, to reduce the adverse
influence of dispersion in switching control timings as well as
asynchronism of A/D operation timings, the microcomputer is given a
large burden for timing controls.
SUMMARY OF THE INVENTION
[0010] In view of the above-described problems, the present
invention has an object to provide a flying capacitor voltage
detecting apparatus which is capable of improving the measuring
accuracy while preventing the circuit arrangement from becoming
complicated.
[0011] In order to accomplish the above and other related objects,
the present invention provides a first voltage detecting apparatus
for a combination battery including a multiplexer type flying
capacitor voltage detecting circuit, a synchronous control type A/D
converter, and a battery controller. The multiplexer type flying
capacitor voltage detecting circuit has an input multiplexer and an
output side sampling switch. The operation timing of the flying
capacitor voltage detecting circuit is controlled in response to an
entered switching control signal for time sequentially executing
voltage read-in processing and voltage read-out processing to
detect the voltage of a plurality of battery modules of a
combination battery in a time sequential fashion. The synchronous
control type A/D converter, whose operation timing is controlled in
response to an entered activation signal, is provided for sample
holding and A/D converting an analog output voltage of the flying
capacitor voltage detecting circuit and also holding a digital
voltage signal as a resulting output until a succeeding digital
voltage signal is obtained. The battery controller, whose operation
timing is controlled in response to an entered transfer command
signal, is provided for reading the digital voltage signal produced
from the A/D converter and storing the readout digital voltage
signal into a data storage area assigned to each of the battery
modules.
[0012] Furthermore, according to the first voltage detecting
apparatus of the present invention, the battery controller includes
a timing table on which generation timings of the switching control
signal, the activation signal, and the transfer command signal are
all determined on a common time axis. And, timing control for the
flying capacitor voltage detecting circuit, the A/D converter, and
the battery controller is carried out by outputting the switching
control signal, the activation signal, and the transfer command
signal to the flying capacitor voltage detecting circuit, the A/D
converter, and the battery controller at the timing regulated in
the timing table and according to an order memorized in the timing
table.
[0013] With this arrangement, it becomes possible to provide a
flying capacitor voltage detecting apparatus which is capable of
improving the measuring accuracy while preventing the circuit
arrangement from becoming complicated.
[0014] The first voltage detecting apparatus according to this
invention successively reads out event information at predetermined
time intervals. Each event information consists of a switch
operation event memorized beforehand in a table for commanding a
turning on-and-off operation of analog switch group, an A/D
activation event memorized beforehand in a table for commanding
activation of the A/D converter, and a memory storage event
memorized beforehand in a table for storing the digitized block
voltage into a memory corresponding to each battery block. The
first voltage detecting apparatus executes the port processing or
the data conversion processing corresponding to the event
information, produces a switching pattern for the analog switch
group of the flying capacitor voltage detecting circuit, and
sequentially measures block voltages.
[0015] With this arrangement, it becomes possible to simplify the
conditional branch processing and accordingly increase the speed of
a processing apparatus. The delay time in the processing apparatus
can be shortened. It becomes possible to suppress the fluctuation
in the switching pulse width as well as the delay in A/D
activation. Thus, the voltage detection having less dispersion is
realized.
[0016] More specifically, according to the control of a
conventional flying capacitor voltage detecting circuit, each group
has its own timing counter for determining the timings of events
although all of the groups are controlled according to a timing
pulse produced based on the common clock pulse. The timing counter
of each group independently controls the flying capacitor voltage
detecting circuit, the A/D converter, and the battery controller.
Accordingly, in the case that the processing time for each module
voltage is short in the multiplexer type flying capacitor voltage
detecting circuit or the like, there is the possibility that
microcomputer cannot finish the processing within a scheduled time.
In other words, the timing synchronization among the flying
capacitor voltage detecting circuit, the A/D converter, and the
battery controller cannot be maintained adequately.
[0017] On the contrary, this invention prepares a timing table for
producing the switching control signal which regulates a switching
timing of the flying capacitor voltage detecting circuit, the
activation signal which regulates a switching timing of the A/D
converter, and the transfer command signal which regulates read-out
and read-in (i.e., port opening) timings from the A/D converter to
a predetermined storage area of the microcomputer. This timing
table operates on a common time axis (by using a common timing
counter).
[0018] The switching control signal, the activation signal, and the
transfer command signal are sequentially produced at the timings
regulated on the common time axis even when the time allocated to
the processing of each module voltage becomes short due to the use
of a multiplexer. According to this arrangement, timing
relationship among those signals can be surely maintained. Thus,
reliable and excellent module voltage detection can be
realized.
[0019] According to the first voltage detecting apparatus for a
combination battery of the present invention, it is preferable that
the battery controller gives first priority to the output of the
switching control signal supplied to the flying capacitor voltage
detecting circuit in a case that the timing table regulates signal
generation timings in such a manner that the generation timing of
the switching control signal equals to or overlaps with the
generation timing of the activation signal or the transfer command
signal,
[0020] Namely, the processing of the switch operation event is set
and executed earlier than or prior to the processing of the A/D
activation event or the memory storage event. Thus, it becomes
possible to eliminate the fluctuation in the switching pulse width
and realize accurate voltage detection with less dispersion.
[0021] In other words, this invention gives first priority to the
operation of the flying capacitor voltage detecting circuit. The
processing time allocated to the voltage read-in processing, which
is substantially a CR charging operation, is assured sufficiently
without being reduced unwontedly, even when the A/D conversion
processing or the data transfer processing is delayed or
unstable.
[0022] In general, the A/D conversion processing can be carried out
in an overlapped manner with the operation of the flying capacitor
voltage detecting circuit. The activation control of the A/D
converter is simple compared with the control of the multiplexer
type flying capacitor voltage detecting circuit. Causing a little
bit of delay in the A/D conversion processing is not so serious.
Similarly, as the data transfer processing is an operation for
transferring the A/D converted data into a memory, causing a little
bit of delay in the data transfer processing does not give adverse
influence to the accuracy of the voltage detection.
[0023] According to the first voltage detecting apparatus for a
combination battery of the present invention, it is preferable that
the timing table sets the timing of the activation signal in such a
manner that a voltage read-in timing of the A/D converter does not
involve a switching timing of the flying capacitor voltage
detecting circuit and a switching timing for data storage of the
battery controller.
[0024] Namely, it is not necessary to execute the switching
on-and-off processing and the A/D converter activation processing
at the same time. Thus, it becomes possible to prevent the AD
converter from being delayed in activation. Accordingly, it is
always possible to keep a constant time interval from the
turning-on timing of the output analog switch to the sampling
timing. The dispersion in measurement among respective battery
blocks due to leak current of the capacitor can be suppressed.
Furthermore, it becomes possible to prevent the switching noise
from being mixed and entered in the analog input voltage sample
holding operation for the A/D conversion processing.
[0025] According to the first voltage detecting apparatus for a
combination battery of the present invention, it is preferable that
the timing table includes a first small table for designating the
timing of the switching control signal and a second small table for
designating the timing of the activation signal and the transfer
command signal, being respectively regulated on the common time
axis, and the battery controller refers to the first small table at
time intervals shorter than those of the second small table.
[0026] More specifically, according to this arrangement, the table
for producing a switching pattern (i.e., a table memorizing the
switch operation event) is referred to frequently compared with the
table for activating the A/D converter (i.e., a table memorizing
the A/D activation event) or the table for storing the data into a
memory (i.e., a table memorizing the memory storage event). This
makes it possible to produce each switching control signal within a
fine time width without increasing the bit number (data amount) for
the timing control of all signals. It becomes possible to suppress
the frequency in referring to the table for activating the A/D
converter as well as the frequency in referring to the table for
storing the memory. The computing load for the timing control can
be reduced.
[0027] Furthermore, the present invention provides a second voltage
detecting apparatus for a combination battery, including a flying
capacitor voltage detecting circuit, an A/D converter, and a
battery. The flying capacitor voltage detecting circuit has an
input multiplexer and an output side sampling switch and executes
the voltage read-in processing and the voltage read-out processing
in a time sequential fashion to detect the voltage of a plurality
of battery modules of a combination battery. The A/D converter is
provided for A/D converting an analog output voltage of the flying
capacitor voltage detecting circuit into a digital voltage signal.
The battery controller is provided for reading the digital voltage
signal produced from the A/D converter and storing the readout
digital voltage signal into a data storage area assigned to each of
the battery modules. Furthermore, according to the second voltage
detecting apparatus, the battery controller includes a read-out
order memory table for regulating voltage detection order of
respective battery modules. The battery controller writes
identification numbers of battery modules into the read-out order
memory table in order of voltage largeness of respective modules
detected previously. And, the battery controller controls the input
multiplexer of the flying capacitor voltage detecting circuit in
such a manner that, in the next voltage read-out processing of
respective modules, the module voltages are successively read out
in accordance with the order memorized in the read-out order memory
table.
[0028] According to the second voltage detecting apparatus of the
present invention, it becomes possible to suppress the electric
potential change in the flying capacitor which varies in response
to each read-in processing of the module voltage. This makes it
possible to reduce the voltage read-in error or voltage read-out
error in the flying capacitor voltage detecting circuit. It is also
possible to reduce heat generation during the charge/discharge
operation of the flying capacitor.
[0029] The second voltage detecting apparatus of the present
invention is preferably employed in the case that a
current-limiting resistance element is connected in series with an
input side sampling switch of the multiplexer
[0030] The resistance value R of this resistance element and the
capacitance C of the flying capacitor cooperatively constitute a CR
charging circuit working during the module voltage read-in
processing. To accurately read the module voltage into the flying
capacitor, it is necessary to reduce the time constant =CR of this
circuit. In other words, the capacitance of the flying capacitor
needs to be reduced or the resistance value of the resistance
element needs to be reduced. The former tends to increase the KTC
noise and induces voltage reduction due to a parasitic capacitance.
The latter induces deterioration in the current-limiting function
in case of short-circuit accident.
[0031] According to the second voltage detecting apparatus of the
present invention, the module voltage to be read in the next
read-in processing is closest to the module voltage being read in
the present read-in processing. Accordingly, it becomes possible to
reduce the burden of the flying capacitor in the charge/discharge
operation and reduce the read-in error.
[0032] According to the second voltage detecting apparatus of the
present invention, it is preferable to execute the next module
voltage read-out processing in order of largeness of the module
voltage, considering the fact that the charged voltage of the
flying capacitor decreases slightly in response to charged voltage
read-out processing of the flying capacitor. According to the
second voltage detecting apparatus, the flying capacitor should not
be cleared (i.e., reset) after accomplishing the charged voltage
read-out processing. Furthermore, according to the second voltage
detecting apparatus, it is possible to obtain important information
relating to occurrence of excessive charging at an earlier stage of
the read-out processing of each module voltage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description which is to be read in conjunction with the
accompanying drawings, in which:
[0034] FIG. 1 is a block diagram showing a voltage detecting
apparatus for a combination battery in accordance with a first
embodiment of the present invention;
[0035] FIG. 2 is a circuit diagram showing a practical example of
the flying capacitor voltage detecting circuit shown in FIG. 1;
[0036] FIG. 3 is a flowchart showing the operation of the voltage
detecting apparatus for the combination battery shown in FIG.
1;
[0037] FIG. 4 is a timing table which is referred to in the
flowchart shown in FIG. 3;
[0038] FIG. 5 is a timing chart showing the contents of the timing
table shown in FIG. 4; and
[0039] FIG. 6 is a flowchart showing the processing for designating
the read-out order of battery modules of the voltage detecting
apparatus for a combination battery in accordance with a second
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] Preferred embodiments of the voltage detecting apparatuses
for a combination battery in accordance with the present invention
will be explained hereinafter with reference to attached
drawings.
First Embodiment
[0041] <Overall Arrangement>
[0042] FIG. 1 shows a circuit block diagram of a voltage detecting
apparatus for a combination battery in accordance with a first
embodiment of the present invention. The potential difference
(i.e., a module voltage) of respective battery modules of a
combination battery 1 is successively selected by an input side
multiplexer 2 of a flying capacitor voltage detecting circuit FC
and is stored in a flying capacitor 3.
[0043] After an arbitrary module voltage is stored into the flying
capacitor 3, each sampling switch (i.e., input side sampling
switch) of the multiplexer 2 is turned off. The electric potential
of the flying capacitor 3 becomes a floating electric potential.
Then, an output side sampling switch 4 of the flying capacitor 3 is
turned on. The charged voltage of the flying capacitor 3 is applied
between a pair of input terminals of a differential amplification
circuit 5.
[0044] The differential amplification circuit 5 amplifies an analog
input voltage and produces an output supplied to an input side of
an A/D converter 6.
[0045] The A/D converter 6 has a function of sample holding the
input voltage and A/D converting the sample held voltage, and then
holding a digital voltage signal resulting through the A/D
conversion at its output port. The A/D converter 6 executes these
sample holding, A/D converting, and output port overwriting
operations in predetermined sequence with predetermined time
intervals, in response to an A/D converter activation signal
(hereinafter, simply referred to as "activation signal") entered
from the outside into a built-in timing formation circuit so as to
serve as an origin of the sequence.
[0046] A battery controller 7, having a microcomputer-based
arrangement, outputs switching control signals to the multiplexer 2
and the output side sampling switch 4 to control the switching
timings of these switching elements. Furthermore, the battery
controller 7 outputs an activation signal to the A/D converter 6 to
control the timing of its sample holding operation and output port
overwriting operation. Furthermore, the battery controller 7
produces a transfer command signal and fetches the digital voltage
signal held at the output port of the A/D converter 7 into a
corresponding area of its own memory which is designated beforehand
at the timing designated by the transfer command signal. In the
process of fetching the digital voltage signal into its own memory,
the battery controller 7 executes the physical value conversion
(i.e., LSB conversion, gain and phase corrections, etc.) for
converting the data format into appropriate form being easily
handled in the microcomputer. Although the A/D converter is
separated from the microcomputer in the above-described
explanation, it is possible to arrange the microcomputer so as to
incorporate the A/D converter.
[0047] <Arrangement of Flying Capacitor Voltage Detecting
Circuit FC>
[0048] FIG. 2 shows the flying capacitor voltage detecting circuit
FC.
[0049] The combination battery 1 consists of a total of seven
battery modules VB1 to VB7 which are connected in series. Each of
the battery modules VB1 to VB7 includes the same number of cells
which are connected in series. The multiplexer 2 consists of a
total of eight current-limiting resistance elements R1 to R8 and
the same number of sampling switches S1 to S8 serially connected to
corresponding current-limiting resistance elements R1 to R8,
respectively.
[0050] The flying capacitor 3 consists of first and second flying
capacitors C1 and C2 which have the same capacitance. The sampling
switches S1 and S5, i.e., the (4 m+1).sup.th sampling switch, are
connected at one end to the (4 m+1).sup.th terminal of the
combination battery 1 and at the other end to an independent
terminal of the first flying capacitor C1, where m is 0 or positive
integer. The sampling switches S3 and S7, i.e., the (4
m+.sub.3).sup.th sampling switch, are connected at one end to the
(4 m+3).sup.th terminal of the combination battery 1 and at the
other end to an independent terminal of the second flying capacitor
C2, where m is 0 or positive integer. The sampling switches S2, S4,
S6, and S8, i.e., the 2 m.sup.th sampling switches, are connected
at one end to the 2 m.sup.th terminal of the combination battery 1
and at the other end to a connecting terminal of the flying
capacitors C1 and C2, where m is 0 or positive integer and
accordingly 2 m is an even number.
[0051] The output side sampling switch 4 consists of a total of
three sampling switches S10 to S12. The sampling switch S10
connects the independent terminal of first flying capacitor C1 via
an input resistance element R12 to a first input terminal x of a
first operational amplifier 31. The sampling switch S12 connects
the independent terminal of second flying capacitor C2 via an input
resistance element R12' to a first input terminal x' of a second
operational amplifier 32. And, the sampling switch S11 connects the
connecting point of the flying capacitors C1 and C2 to second input
terminals Y and Y' of the operational amplifiers 31 and 32 via
input resistance elements Rel and Rel', respectively.
[0052] The first and second operational amplifiers 31 and 32,
cooperatively constituting a differential voltage detecting
circuit, serve as the analog differential amplification circuit 5.
The outputs of these operational amplifiers 31 and 32 are
respectively sent to two A/D converters ADC1 and ADC2 which serve
as the A/D converter 6 shown in FIG. 1.
<Operation>
[0053] First of all, the battery controller 7 turns on the sampling
switches S1, S2, and S3 to read the voltage of battery module VB1
into the first flying capacitor C1 and the voltage of battery
module VB2 into the second flying capacitor C2. Next, the battery
controller 7 turns off the sampling switches S1, S2, and S3 and
turns on the sampling switches S10 to S12 for a predetermined
period of time to read the voltage difference of first flying
capacitor C1 into the first operational amplifier 31 and the
voltage difference of second flying capacitor C2 into the second
operational amplifier 32. In this case, it is possible to execute
the reading operation of the charged voltage of first flying
capacitor C1 and the charged voltage of second flying capacitor C2
in a time sequential fashion. Next, the battery controller 7 turns
on the sampling switches S3, S4, and S5 to read the voltage of
battery module VB3 into the second flying capacitor C2 and the
voltage of battery module VB4 into first flying capacitor C1.
Hereinafter, by executing the switching control in the same manner,
the voltage of each battery module is read out to the A/D converter
6. Although the above-described circuit arrangement provides two
flying capacitors, it is possible to use only one flying capacitor
or increase the total number of flying capacitors to three or
more.
<Timing Control>
[0054] FIG. 3 is a flowchart of the timing control routine showing
an essential part of this embodiment. This timing control routine
corresponds to the operation performed by a timing control section
70 of the battery controller 7 which is a forced interrupt executed
at predetermined time intervals.
[0055] This timing control routine chiefly includes the read-in
processing for reading the information described on a timing table
shown in FIG. 4 at fixed timings, and the command processing for
instructing the switching control for the input side sampling
switches and the output side sampling switches shown in FIG. 2, the
activation of A/D converter 6, and the data transfer processing
(storage operation) from the A/D converter 6 to its own memory in
accordance with the readout information.
[0056] The timing table in FIG. 4 shows execution events (i.e.,
execution instructions) to be executed at respective interrupt
timings. The "time" shown in FIG. 4 represents each interrupt
timing occurring at predetermine time intervals. This timing table
describes switching control signal output commands (i.e., switch
operation event), activation signal output commands (i.e., A/D
activation event), and transfer command signal output commands
(i.e., memory storage event) which are used in the process of
reading the module voltage from all battery modules of the
combination battery and storing the readout voltage data into the
memory.
[0057] All of interrupt timings are determined and regulated on an
ordinate axis (i.e., common time axis) of the timing table, in
which progress of time accords to the counting action of a single
(i.e., common) clock counter. This clock counter is a cyclic
counter which counts all of the above-described interrupt timings
listed on the timing table, and waits for a while (e.g., the
above-described predetermined time interval according to this
embodiment) so that the event being read out at the final interrupt
timing can be completely performed. After this waiting time has
passed, the clock counter is reset to restart the counting
operation.
[0058] The fixed-time interrupt routine shown in FIG. 3 is
activated when the count value of a built-in clock counter reaches
the interrupt timing. First, the read-out processing of switch
operation event and succeeding transmission stage of the switching
control signals are carried out in the following manner.
[0059] The timing control section 70 accesses the switch operation
event on the timing table (in step S101), and makes a judgment as
to whether or not there is any switch operation event (in step
S102). When no switch operation event exists (i.e., NO in step
S102), the control flow jumps to step S104. When there is any
switch operation event (i.e., YES in step S102), the timing control
section 70 outputs a switching pattern of switching control signals
corresponding to the readout switch operation event to the flying
capacitor voltage detecting circuit FC (in step S103) and then
proceeds to step S104.
[0060] Next, the read-out processing of A/D activation event and
succeeding transmission stage of the activation signal are carried
out in the following manner.
[0061] The timing control section 70 accesses the A/D activation
event on the timing table (in step S104), and makes a judgment as
to whether or not there is any A/D activation event (in step S105).
When no A/D activation event exists (i.e., NO in step S105), the
control flow jumps to step S107. When there is any A/D activation
event (i.e., YES in step S105), the timing control section 70
outputs an activation signal corresponding to the readout A/D
activation event to the A/D converter 6 (in step S106) and then
proceeds to the step S107.
[0062] Next, the read-out of processing of memory storage event and
succeeding transmission stage of the transfer command signal are
carried out in the following manner.
[0063] The timing control section 70 accesses the memory storage
event on the timing table (in step S107), and makes a judgment as
to whether or not there is any memory storage event (in step S108).
When no memory storage event exists (i.e., NO in step S108), the
timing control section 70 terminates this routine. When there is
any memory storage event (i.e., YES in step S108), the timing
control section 70 executes a data transfer processing
corresponding to the readout memory storage event to cause the
microcomputer to read and correct the digital voltage signal held
at the output port of the A/D converter 6 (in step S109). Then, the
timing control section 70 stores the obtained voltage data into a
designated memory area (in step S110). In this case, it is possible
to execute the above-described voltage correction at different
timing.
[0064] By carrying out respective controls explained in the
flowchart of FIG. 3 at the above-described interrupt timings,
various operation events listed on the timing table of FIG. 3 are
sequentially executed and the voltage detecting processing for
respective modules is accomplished thoroughly. FIG. 5 is a timing
chart showing the contents of the timing table shown in FIG. 3.
<Effect of Embodiment>
[0065] First, according to the above-described embodiment, as shown
in FIG. 3, in the fixed-time routine for the timing table read-in
processing and succeeding output of the timing signal, generation
of the switching control signal is executed earlier than or prior
to generation of the activation signal or the transfer command
signal. This arrangement effectively prevents the flying capacitor
voltage detection from being delayed, so that the flying capacitor
voltage detection can be surely accomplished prior to the A/D
conversion or the data transfer. In other words, no adverse
influence is given to the later-performed A/D conversion or the
data transfer processing. Furthermore, it becomes possible to
suppress the fluctuation in the switching pulse width from.
Accurately securing the charging time of each capacitor is
feasible.
[0066] Namely, in an event that any A/D activation event or any
memory storage event coexists with a switch operation event at the
same interrupt timing on the timing table, the present invention
gives first priority to the processing of the switch operation
event.
[0067] Furthermore, as shown in FIGS. 4 and 5, activation of the AD
converter is performed within a period of time where the switching
control signals supplied to the input side sampling switches and to
the output side sampling switches of the flying capacitor voltage
detecting circuit are stable (i.e., not unchanged). This is
effective to eliminate delay in the activation of AD converter.
Thus, it becomes possible to execute the sampling at the constant
timing (i.e., when a predetermined time has passed) after the
output analog switch is changed. It becomes possible to eliminate
error or dispersion in the measured voltage occurring due to
superposition of the switching control signal.
[0068] Furthermore, the timing table includes a first small table
(i.e., the switch operation event table) for designating the timing
of the switching control signals and a second small table (i.e.,
the A/D activation event table and the memory storage event table)
for designating the timings of the activation signal and the
transfer command signal, being respectively determined and
regulated on the common time axis. The battery controller
(frequently) refers to the first small table at time intervals
shorter than those of the second small table. Accordingly, the
table reference processing can be simplified.
Second Embodiment
[0069] FIG. 6 is a flowchart showing the operation in accordance
with another embodiment of the present invention.
[0070] This embodiment is, in short, characterized in that the next
read-out order of module voltages is determined with reference to
the largeness of respective module voltages being previously read.
To simplify the explanation, this embodiment uses only one flying
capacitor. However, it is needless to say that a plurality of
flying capacitors can be used as shown in FIG. 2. In this case,
each flying capacitor is provided for a group of module voltages
and in each group the order of each battery module is determined
considering the largeness of the module voltage. The determined
order is memorized in the table with the identification number of
respective battery modules. And, the next read-out processing is
executed based on this table.
[0071] First, the timing control section 70 checks whether or not
the read-out processing (including memory storage processing) for
all of the module voltages is finished (in step S200). When the
read-out processing is not finished yet (i.e., NO in step S200),
timing control section 70 terminates this routine to return to the
main routine. When the read-out processing is thoroughly finished
(i.e., YES in step S200), the timing control section 70 rearranges
the detected module voltages in order of largeness and stores the
identification number of each module voltage into a read-out order
memory table (in step S202). The order adjusted or rearranged in
this step is referred to as reading-out order in the next read-out
processing. Then, the timing control section 70 rearranges the
switch operation event and the memory storage event listed on the
timing table of FIG. 4 according to the read-out order memorized in
this table (in step S204).
[0072] With this arrangement, each flying capacitor can read almost
the same voltage (although it becomes small a little bit) in every
read-in processing. Thus, it becomes possible to reduce the
charge/discharge current of the flying capacitor and accordingly it
becomes possible to effectively prevent the read-in accuracy from
deteriorating depending on a CR time constant.
[0073] In the case that the timing table of FIG. 3 is frequently
rewritten as explained in this embodiment, the timing table should
be stored in RAM. On the other hand, when the timing table is
unchanged as described in the first embodiment, it is preferable to
store the time table in PROM or in ROM.
* * * * *